Precision positioning means for sound heads



'Aug' 1l 1942' w. L.. wOoLF ET Al. 2292856 PRECISION PSIIIONING MEANSFOR SOUND HEADS Filed March l, 1940 2 Sheets-Sheet l Aug. 11, 1942. w. 1wooLF ET Ax.

.PRECISION POSITIONING MEANS FOR SOUND HEADS Filed March l, 1940 2Sheets-Sheet 2 Patented Aug. 11, 1942 PRECISION POSITIONING MEANS FORSOUND HEADS William L. Woolf, Bayside, Long Island, and Edgar L. Steed,Woodside, Long Island, N. Y., assignors, by mcsne assignments toAmertype Recordgraph Corporation, Elizabeth, N. J., a

corporation of Delaware Application March 1, 1940, Serial No. 321,750

f s claims.

This invention relates to recording and reproducing mechanism and moreparticularly to a device of this kind wherein the record consists of aplurality of parallel sound tracks made by a stylus engaging a recordmedium in the form of a strip or film.

The object of ths invention, generally stated, is to provide precisionpositioning means for the recording and reproducing heads which headsmay collectively be referred to as sound heads.

More specifically stated, the invention has for one of its objects theprovision of means for shifting the sound heads from one sound track toanother at the appropriate time and to the precise extent and to meansfor preventing the shifting means from running the stylus off the film.

A further object is the provision of a track-- ing device whereby thepick-up needle automatically finds the proper groove and the properlocation in the groove.

The various features of the invention whereby the above mentioned, andother objects, are accomplished will be better understood from thefollowing detailed description and claims when taken, in connection withthe accompanying drawings in which:

Figure 1 is a perspective view showing the principal parts of themechanism more or less diagrammatically;

Figure 2 is an elevation showing the sound heads and means for`controlling their engagement or disengagement with the record medium;and for aligning the pick-up head with the recording head;

Figure 3 is a plan of the parts 4shown in Figure 2; and l Figure 4 is asection of the film, very much enlarged, showing several sound trackswith cross-over tracks.

Referring to Figure 1, the iilm 2 is provided with perforations at itsedge, which perforations are engaged by the teeth of a sprocket 4secured to a shaft 5. The shaft carries a fly wheel E, the periphery ofwhich is engaged by a roller 8 driven from a motor I0. The recordinghead I2 is provided with a rearwardly extending tone arm I4 pivoted forvertical movement between two arms I5 which project from and form partof a sleeve I6. The tone arm is supported by trunnion screws I8 oneyonly of which is shown in Figure 1, but both are shown in Figure 3. Therecording 'head is therefore capable of ver- 20 to be moved into and outof engagement with' the record strip, such movement being under controlof a cam to be later described. It is held against sidewise movement,relative to the sleeve I6, by the trunnions I8.

The pick-up head 22 carries a stylus 23 by which the record made by thestylus 20 is reproduced. The pick-up head is connected to the recordinghead in such manner that the pick-up head may be moved verticallyindependently of the recording head and also may be permitted a slightlateral movement in respect thereto. To this end the pick-up head hassecured to it a bar 24. The rear end of this bar kis pivoted in abracket 25 which bracket is in turn pivoted to the tone arm. This pivotis shown in dotted lines in Figure 3 and indicated by the referencecharacter 2li.l Thus the pick-up head may move in a vertical vdirectionby pivoting about 26 and may move slightly in a horizontal direction bypivoting about the pivots carried by the bracket 25.

A shaft 21 carries a roller 28 for supporting the film in contact withthe stylus 20 of the recording head when the recording head is inrecording position. l

Since it is contemplated to record a great many parallel sound tracks onthe record medium, it is necessary that these tracks be as closetogether as is practically feasible. For instance, in a record strip ofthe width of the standard moving picture lm, namely 35 centimeters, itis practical to record more than 100 parallel sound tracks on such a lm.

It is contemplated furthermore that the film be a continuous oneandtherefore it is desirable to shift the sound heads from one sound trackposition to the next, at predetermined intervals.

According to this invention, this shifting is done while the recordingstylus is in engagement with the record medium so that the record madeby the recording stylus is a continuous one. In reproducing, of course,the reproducing stylus 23 follows the sound tracks made by the recordingstylus 20. Since the sound tracks are very close together, it isessential that the lateral movement from one sound track position to thenext be effected with the greatest accuracy and the mechanism by whichthis is accomplished will now be described.

The sleeve I6 which supports the sound heads is interiorly threaded andsimilar threads formed on shaft 30 engage the threads of this sleeve.

The shaft 30 is supported by brackets 32 only tical movement to enableits recording stylus one 0f Which iS Shown in Figure 1, Since to showthe other would obscure some of the essential parts of the mechanism. Itis also to be understoodvthat the shafts 5 and 21 are also properlysupported although these supports are not shown.

The shaft 30 extends to the right and carries a knob 33, by which it maybe rotated manually. The exact amount of rotation of the shaft 30 tocause the precise degree of lateral movement of the sound heads iscontrolled by a ratchet 34 secured to a sleeve 35 which sleeve is inturn fastened to the shaft 30 by a screw 36. The ratchet 34 is shown ashaving eight notches 31 with an intermediate portion 36 between eachnotch. 'I'he ratchet 34 is normally held locked by a pawl 40 which seatsin one of the notches 31. This pawl and a notch 31 are so shaped thatthe pawl holds the ratchet 34 from rotation in a clockwise direction butpermits rotation in an anti-clockwise direction.

Means are provided whereby at predetermined intervals in the movement ofthe record strip, the pawl 40 is released from a notch 31 and theratchet 34 and shaft 30 are driven one-eighth of a rotation, at whichtime the pawl 40 seats into the next adjacent notch and positively stopsthe rotation of the shaft 30 and thereby accurately determines theextent of lateral movement of the sound heads.

The sleeve 35 also carries a toothed wheel 4| which engages a pinion 42connected to the shaft of an ordinary counter 43. The pawl 40 not onlyacts to limit the rotation of the shaft 30 but also limits themovementnof the counter whereby an accurate indicationis given of thesound track which is being engaged at any time by the stylus or thestylus 23. The ythreads on the shaft 30 are such that one-eighthrotation of said shaft will move the sound heads a distance from onesound track to the next when the ratchet 34 is moved in a clockwisedirection from one notch to the next. This will result in moving thestylus across -the film from left to right with step `by step movement.

When it is desired to position the stylus to the extreme left or to someintermediate track position, the knob 33 is turned in an anti-clockwisedirection, which the pawl 40 permits.

The movement of the sound heads step by step across the film is broughtabout by motor means and in the embodiment illustrated a separate motor44 is provided for this purpose. The motor operates through a reductiongear located in the gear box 45 and is connected to the shaft 30 througha friction clutch 46. With the parts in the position shown in Figure l,the pawl 40 is held seated in a notch of the wheel 34 by means of alight spring 41, and assuming that the motor I0 is in operation, thefilm 2 is being fed through the machine in the direction of the arrowshown on the film. It is contemplated that at each complete revolutionof the nlm, the sound heads be moved one step to the right. In orderthat this may be brought about, the ratchet 34 must be released and themotor 44 started.

These operations are initiated through means of an electricallyconducting portion 43 carried by the film and extending on both sidesthereof. When this electrically conducting portion 43 passes betweencontacts 50, one on each side of the film, a circuit is closed whichenergizes relay 60 which in turn closes a circuit which energizessolenoid 61 of which the pawl 40 constitutes the armature. Release ofthe pawl 40, closes a circuit through the motor due to the pawl ridingon the high part 36 of a tooth of wheel 34. The motor through thereduction gearing 45 and clutch 46 rotates shaft 30. The motor 44receives current until pawl 40 drops into the next notch in the wheel 34at which time the circuit to the motor is broken. The pawl dropping intothe nextnotch positively stops further rotation of ratchet 34 and theshaft 3l and the parts controlled thereby, but the motor may continue torun for a few turns due to the slippage provided by the clutch 46.

'I'he circuits involved in the above operations may be traced asfollows. From terminal B current passes to junction 53, wire 54, andthrough switch 55, which is normally closed, through wire 56 to junction51; along wire 56 to contacts 50; thence along wire 53 leading to relay60. From this relay the current flows through wire 6| back to terminalA. Energization of the relay 66 closes a contact 62 in switch 63 and assoon as said contact is closed, the current passes from junction 51along wire 64 to junction 65 and through wire 66 to solenoid 61. Fromsaid solenoid it passes through switch 63 and wire 6| to terminal A.Energization of solenoid 61 lifts the pawl 40 as already described,which pawl .upon being lifted closes contact at 69 whereby establishinga circuit through the motor 44 which circuit may be traced as follows:from terminal B along wire 54 to switch 55, thence along wires 56 and 64to junction 10 to the motor. From the motor it passes along wire 1| tocontact 69; thence through the pawl 46 which is connected to wire 12,through which the current flows to junction 13 and through wire 14 toterminal A.

From the foregoing it will be apparent that during the continuouslongitudinal movement of the film the sound heads are moved laterallystep by step and if the recording head is in recording position, 'acontinuous sound groove is formed. The distance, however, which the filmtravels during the time that the recording head is making its step ofmovement from one sound track position to the next is very large inproportion to such lateral movement. It is important* that this ratio bequite large so that the angle which the oblique portion of the recordgroove makes with the parallel portion be very small. This is desirablein order to prevent the possibility of one sound track getting too closeto another thereby causing interference when the sound is reproduced.For instance, if the motor i0 is running at such speed as to move therecord strip at about eight inches per second, the speed of the motor41,4 may be such as to cause the lateral movement to occupy about twoand onequarter seconds in moving the recording stylus from one soundtrack position to the next. If this movement occupies two and one-halfseconds, the illm is moved longitudinally a distance of eighteen inchesduring this time. The later movement, however, may be as small asone-one hundred and twentieth of an inch, assuming one hundred twentysound tracks to the inch are being recorded.

The beginning and ending of each cross-over sound track is illustrateddiagrammatically in Figure 4 which is necessarily drawn out ofproportion in order to make the operation readily visible. The numbers Ito 4 at the left indicate four sound tracks. Each point on the soundtracks along the line a-a represents the beginning of the cross-overmovement. The dotted line from track I indicates the path which thestylus would take if it were not moved laterally at this time. The fullline connecting track I with track 2 indicates the path which the stylusactually takes during its lateral movement. The

points along the line b-b indicate the points at which the stylus hascompleted its lateral movement and it `also represents the beginning ofa newsound track. It will also be noted that when the stylus reaches thepoint 2 on the line b-b the counter also registers 2. When the film hasmade a complete cycle, the conducting portion 48 again closes contacts58 and the stylus has arrived at a point along the line a-a of the sound1 track where it is again moved laterally to start newtrack #3, at thepoint 5 on the line b-b. 15

If there was no means to prevent it, the motor would move the stylusentirely of! ofthe lm. This, however, is of course not desirable andmeans to prevent such movement are provided.

This consists of the switch se already referred to. 2o

This switch is normally closed by means of a spring arm contacting astationary conducting element 15. The righi'. hand arm I5 of the sleeveI5 carries a screw 11 which when the recording head starts to movetoward the right after completingthe last track on the right of thefilm, presses against the spring member 15 of the switch 55 therebybreaking the contact and opening the circuits to the motor I8 and to themotor 44. When the spring member 15 is 30 thus moved to open the switch,it is held in open position by a latch provided with a knob 18 by whichthe latch may be moved to release the spring member 15 when it is againdesired to start the motor Il. As long as the switch 55 is 35 closed,current is supplied to the motor I8 but it is not supplied to the motor44 unless the conducting portion 48 of the nlm bridges contacts 50 orthe circuit to motor 44 is otherwise closed.

Manual means are provided for this purpose in 40 the form of a lever 'I8whichcloses a circuit in parallel with the contact 48 and members 58whereby the motor circuit may be closed at any time provided the switchis also closed. By

means of the lever 18 therefore, the recording 45 head may be moved stepby step towards the right to position it at any desired sound track. r

Current to motor Il may be traced as follows:

From terminal B to junction 51, wire 54 to switch c 55, thence by wire88 to junction 8I. From here 50 it passes along wire 82 to motor I0.Returning,

the current flows along wire 83 to junction 84,

to wire 14, to terminal A.

When the recording head is stepped across the film by lever 19, it isdesirable that the recording 55 head be in raised position, otherwisethe stylus 20 might damage tlle film by scraping across it. In theapplication of Henry Flood, Jr., Serial A No; 320,084, med February 21,1940, means are cording head and the pick-up head are controlled 55 asto engagement or non-engagement with the film. The means whereby this isaccomplished is best shown in Figures 2.and 3 and includes a cam shaft85 having a knob 86 at its outer end,

Figure l, whereby the shaft may be rotated in an appropriate manner. Theshaft carries a cam 81 the contour of which is shown in Figure 2. Thiscam engages two rods 88 and 89. The rod 88 has a right angle projection80 at its upper end which extends to the right as shown in Figure 3andbeneaththe bar 24, which it will be recalled is connected directly tothe pick-up head 22 to provide for vertical movement of the head.

The rod 88 is provided with a portion 8| projectlng at right angles fromits upper end and beneath the tone arm I4 of the recording head I2.

With the cam 81 in the position shown in Figure 2 the recording head isin operative position with its stylus 28 in contact with the lm. Thepickup head, however, is in Araised position indicated by full lines inFigure, 2. When the cam 81 is rotated anticlockwise, through an angle ofabout 45 a concentric portion of the cam rides under the rod 88 andholds it in position to maintain the pick-up head 22- in inoperativeposition. The cam is so shaped however, that with the 45 rotation, therod 88 is lifted thereby raising -the stylus 28 out of engagement withthe film.

If .the cam 81 is further rotated in an anticlockwise direction, the rod88 is permitted to move downwardly under the weight of the pickup headwhile the stylus l28 of the recording head remains in raised position.The cam is formed with two shoulders 82 and 85 which when either engagesthe end of the rod 88 or rod 88 prevents further rotation of the cam.Therefore, turning the knob 85 to the right as far .as it will goresults in lifting the pick-up head while permitting the recording headto be inoperative position. By turning the knob 85 to the left oranti-clockwise as far as it will go, results in rendering the pick-uphead operative and the .recording head inoperative. A

One of the objects of the invention has been stated to be the provisionof a tracking device whereby the pick-up needle automatically finds theproper groove and the proper location in the groove. v

'I'he means for accomplishing this result includes a slide member 84adjustably secured to the recording head I2 and a guide in the form oftwo spaced members 86 carried by the pick-up head 22. The guide membersare obliquely spaced relative to each other and converge to a narrowportion, of sufiicient width to barely permit the head of the slide 94to pass. A screw 88 permits accurate alignment of the slide member 84 sothat as the pick-up head 22 is moved vertically from inoperativeposition to a position where its stylus engages the record medium, thestylus is accurately guided to the proper groove and accurately locatedin the groove.

What we claim is: 1. In a recording and reproducing mechanism, arecording head for making a series of parallel sound tracks in a recordmedium, means for moving said recording head from one sound track to thenext and positively arresting it at the end of such lateral movement,means for preventing any lateral movement of said recording head exceptas provided by said lateral moving means, a pick-up head for followingin the same groove formed by the recording head, said recording head andsaid pick-up head being laterally movable together under control of saidlaterally moving means, said pick-up head being capable of a slightlateral movement independent of said recording head, means for movingthe v pick-up head from reproducing to non-reproducing position or viceversa, and means for correcting any lateral displacement of the pick-uphead relative to the recording head as the pickup head is moved fromnon-engaging to engaging position relative to the recording medium.

2. In a sound recording mechanism, a recording head and a record medium,a screw threaded shaft operatively related to said head for moving itstep by step transversely of the record medium, a locking disk on saidshaft, means engaging said disk normally preventing rotation thereof inone direction and a motor operatively related to said shaft for rotatingit, a circuit for said motor normally open, and means controlled by therecord medium for releasing said disk rotation preventing means saidlatter means on its release closing the circuit to said motor.

3. In a sound recording mechanism, a recording head and a record medium,a screw threaded shaft operatively related to said head for moving itstep by step transversely of the record medium, a notched disc on saidshaft, a pawl for engaging the notches in said disc, normally preventingrotation thereof in one direction, a motor operatively related to saidshaft for rotating said shaft and disc, a circuit for said motornormally open and means controlled by the record medium for releasingsaid pawl from the notch with which it may, at the moment, be engaged,said pawl by its releasing movement closing the circuit to said motor.

4. In a sound recording mechanism, a recording head and a record medium,a screw threaded shaft operatively related to said head for moving itstep by step transversely of the record medium, a notched disc on saidshaft, a pawl for engaging the notches in said disc, normally preventingrotation thereol' in one direction, a motor operatively related to saidshaft for rotating said shaft and disc, a circuit for said motornormally open and means controlled by the record medium for releasingsaid pawl from the notch with which it may, at the moment be engaged,said pawl by its releasing movement closing the circuit to said motor,said pawl on dropping into a succeeding notch in said disc acting tobreak,

the motor circuit and positively to stop rotation of said notched disc.

5. In a sound recording mechanism, a recording head, a record strip,means operatively related to said head for moving it step by steplaterally of said strip said means including a motor and a circuittherefor normally open, means, including a ratchet and a pawlcooperating therewith, normally locking said head against lateralmovement, means controlled by said record strip and operatively relatedto said pawl for releasing it from said ratchet and means brought intoaction on release of said pawl to close said motor circuit.

WILLIAM L. WOOLF. EDGAR L. STEED.

